1. Field of the Invention
The present invention relates to a light source device for an endoscope system.
2. Description Related to the Prior Art
In medical fields, it has become common to perform diagnosis through observing an object of interest (hereinafter simply referred to as the object) in a body cavity with the use of an endoscope system. The endoscope comprises an endoscope, alight source device, and a processor device. The endoscope has an insert section to be inserted into the body cavity. The light source device generates illumination light, which is applied to the object. The processor device obtains an image signal, which is generated by imaging the object through capturing the illumination light reflected from the object, and applies various types of signal processing to the image signal to produce an image of the object.
The endoscope, the light source device, and the processor device are connected to each other through a universal cord extending from a proximal end of the endoscope. The illumination light generated by the light source device is transmitted through a light guide, which extends inside the universal cord and the insertion section, and then applied to the object from a distal end portion of the insert section. The processor device controls an image sensor, which is provided in the distal end portion of the insert section, through electric wiring provided inside the universal cord and the insert section, and obtains the image signal outputted from the image sensor.
In the endoscope system thus configured, the universal cord is easily attached to and detached from the light source device and the processor device, allowing cleaning of the endoscope. Despite the easiness of the connection, the universal cord must be securely connected optically and electrically to the light source device and the processor device. In particular, it is desirable to establish highly precise optical coupling or connection so as to utilize the illumination light efficiently and observe the object with adequate brightness.
There is one type of the light source device which uses a lens to make the illumination light enter the universal cord connected. There is another type of the light source device which incorporates a light guide. The illumination light is transmitted by connecting the universal cord's light guide (hereinafter may referred to as the cord-side light guide) to the incorporated light guide (hereinafter may referred to as the source-side light guide). Among the light source devices which transmit the illumination light by connecting the cord-side light guide to the source-side light guide, there is known a light source device with a mechanism to automatically adjust the position of the source-side light guide at the time of connecting the cord-side light guide to the source-side light guide, so as to establish the highly precise optical coupling or connection (see Japanese Patent No. 5277187 and U.S. Pat. No. 8,517,922 (corresponding to Japanese Patent Laid-Open Publication No. 2006-158859)). Among the light source devices which use the lens to make the illumination light enter the cord-side light guide, there is known a light source device with a mechanism to position the cord-side light guide such that the optical axis of the cord-side light guide is coincident with the optical axis of the lens at the time of connecting the universal cord (see Japanese Patent No. 3089950).
The light guide is flexible, and bending the light guide does not cause loss in the amount of the illumination light. In the case where the light source device transmits the illumination light by connecting the cord-side light guide to the source-side light guide, the illumination light is transmitted to the cord-side light guide with high efficiency by automatically adjusting the position of an end portion of the source-side light guide as described in the Japanese Patent No. 5277187 and the U.S. Pat. No. 8,517,922. However, in the case where the light source device uses the lens to make the illumination light enter the cord-side light guide, a shifting or a displacement in the position of the lens may reduce the incidence efficiency of the illumination light into the cord-side light guide if the lens is moved without care in a manner similar to the positional adjustment of the end portion of the source-side light guide described in the Japanese Patent No. 5277187 and the U.S. Pat. No. 8,517,922.
In the case of the light source device which uses the lens to make the illumination light enter the cord-side light guide, the position of the lens is fixed and the cord-side light guide is aligned with the lens by inserting the cord-side light guide into an insertion hole which is situated in a specific position relative to the fixed lens as described in the Japanese Patent No. 3089950. Thereby the illumination light is transmitted with high efficiency. However, as compared with the case where the alignment is performed using a movable mechanism as described in the Japanese Patent No. 5277187 and the U.S. Pat. No. 8,517,922, a special care may be needed to connect the universal cord to the light source device depending on positioning accuracy of the cord-side light guide. This may reduce the easiness of the connection. In the case where the cord-side light guide needs to be positioned with extra high accuracy, the end portion of the cord-side light guide may be damaged by careless or rough insertion into the insertion hole.